This invention relates to a measurement device for use in the milling of compressor blade ring segments.
Compressor stator blades are typically seated in a plurality of arcuate segments that combine to form an annular ring of segments each containing a plurality of blades. The blades are typically secured to the segments with a dovetail arrangement wherein a male dovetail formed at the base of the blade is slidably received within a dovetail slot in the segment. The dovetail grooves in the segments may be formed by a milling process, but the fixturing required to hold the segment does not insure that a particular reference point can be consistently and repeatably achieved. This reference point is measured from the end edge of the segment to the center of the first dovetail groove in the segment. This reference point must be accurate for each segment in order to insure the proper spacing of blades for the specific stage in the compressor of the turbine. If the spacing is incorrect, turbulent air flow could occur resulting in decreased efficiency of the turbine.
The present invention provides a manual gage assembly that verifies the consistency of the machine and the fixture while running production parts. In the exemplary embodiment, the gage assembly includes a gage body incorporating a conventional dial indicator gage that works in combination with a slide gage designed to be received in the first dovetail slot formed in the segment. The gage body includes a sloped edge that corresponds generally to the sloped edge of the dovetail groove, along with an interior right side edge that is adapted to engage the right side edge of the segment. The dial indicator is supported in the body, with the stem of the indicator passing through a bore in the gage body and opening along the sloped surface. The slide gage component is dimensioned to fit snugly in the dovetail groove, and a fixed pin is centered on the slide gage such that the pin will lie on a longitudinal center line of the dovetail groove when the slide gage is installed in the groove. The pin is also located so as to be centered between the side edges of the segment. With the slide gage inserted into the slot, the gage body is then located on the segment such that the body is engaged with a top surface of the segment and along a right side edge of the segment. With the slide gage so located, the stem of the dial indicator will engage the fixed pin on the slide gage and will measure the distance from the top or end edge of the segment to the center of the dovetail slot. This measurement is often referred to as the xe2x80x9cpoint zeroxe2x80x9d dimension and is used as the reference dimension for milling all of the other dovetail grooves within the segment.
Accordingly, in one exemplary embodiment, the invention relates to a gage assembly for measuring a distance (d) from an end edge of a blade segment to a center location of a groove formed in the segment comprising a gage body having at least two reference surfaces adapted to engage edges of the segment; a dial indicator gage having a dial and a stem, the stem passing through a portion of the gage body; and a slide gage adapted for insertion into the groove, the slide gage fitted with an element that, in use, aligns with the stem of the dial indicator gage.
In another aspect, the invention relates to a gage assembly for measuring a distance (d) from an edge of a blade segment to a center location of a groove formed in the blade segment comprising a gage body having at least two reference surfaces adapted to engage edge surfaces of the segment and a sloped edge configured to match a corresponding angled edge of the groove; a dial indicator gage having a dial and a stem, the stem passing through a portion of the gage body and opening through the sloped edge; and a slide gage adapted for insertion into the groove, the slide gage fitted with an element that, in use, aligns with the stem of the dial indicator gage; wherein one of the reference surfaces comprises a pin, and the other of the reference surfaces comprises a beveled surface extending along a side edge of the gage body.
The invention will now be described in detail in connection with the drawings identified below.